the dynamic InnoDB plugin, ha_innodb.so.  This libtool option cannot
be used on every target platform.  For instance, the AMD64 (x86_64) ABI
mandates position-independent code (PIC) in dynamic shared objects.

Makefile.am: Use $(INNODB_CFLAGS) and $(INNODB_DYNAMIC_CFLAGS) in
target-specific CFLAGS and CXXFLAGS variable definitions.

plug.in: Instead of appending to the MySQL-wide CFLAGS, introduce
the variables INNODB_CFLAGS and INNODB_DYNAMIC_CFLAGS.  Depending on
$target_cpu, append -prefer-non-pic to INNODB_DYNAMIC_CFLAGS.